Method of producing composite metal products



July 1942- 'T. B. CHACE 2,291,026

METHOD OF PRODUCING COMPOSITE METAL PRODUCTS Origihal Filed I Jec. 26, 1939 3 Sheets-Sheet 1 I E? J. I 25 PAE'HEA TF0 mar/m SLAB BEING vwrw/m w/v m0 MOL mv BATH orsmc 0/? FL ux ii: BACKING SLAB BQCKI/VG SLAB /N TRANS/T r0 MOULD I Z4! 6% Wt 27 1 v v} LBAc/mve SLAB f") i" W Thomas 3. 677006 y 1942- T. B. CHACE 2,291,026

METHOD OF PRODUCING COMPOSITE METAL PRODUCTS I I v Original Filed Dec. 26," 1939 3 Sheets-Sheet 2 f ik g: //BACK//VG SLAB w 1'? ii 2 3 \27 U31- 28 15),

Thomas B. Chczce I I I m,

July 28, 1942. T. B. CHACE 2,291,026

METHOD OF PRODUCING vCOMPOSITE METAL PRODUCTS Original Filed Dec. 26,, 1939 3 Sheets-Sheet 3 2705x7707.- BAC/fl/VG SLAB Thomas B. Chace Patented July 2, 1942 STATES P OFFICE METHOD OF rnonucmo comrosrr METAL PRODUCTS Original application December 26, 1939, Serial No. 310,894. Divided and this application March 6, 194-1, Serial No. 382,006

2 Claims. (Cl. 22-204) My invention relates, generally, to a method of manufacturing composite metal "slabs and it has particular relation to the making of such slabs by casting a cladding metal onto one or more surfaces of a backing slabdisposed in a vertical mould.

This application is a division of my copending application, Serial No. 310,894, filed December 26, 1939.

An important object of my invention is to provide an improved method of preventing oxidationof the surface of a backing slab while it is being preheated and then transferred to a mould for casting a cladding metal layer thereon.

Another important'object of my invention is to provide an improved method of cladding a facing metal onto a backing metal by casting in vertical moulds to obtain a diffused bond be- 7 tween the facing metal and the backing metal that is capable of being worked without the cladding metal separating from the backing metal. a

' A further object of my invention is to provide an improved method of cladding a facing metal art with the manner of carrying the method of my invention into effect, reference may be had to .the following detailed description, taken in con- Junction with the accompanying drawings, in which:

Figure 1 is a vertical sectional view of a soaking pit in which a slab of backing metal is pre heated in a flux or slag-bath;

Figure 2 shows how the surface of the backing slab is prevented from contacting with all by the coating of slagor flux while it is being transferred from the soaking pit'to the mould;

Figure3 is a'vertical sectional view of one embodiment of the improved mould construction,

showing the backing slab in place and the cladding metal being poured;

ployed in connection with the various types of moulds shown in the drawings;

'Figure 7 is a top plan view of a mould that is arranged to clad the opposite sides of a backing slab;

Figure 8 is a view in side elevation 'of the construction shown in Figure 7, one-half of the separable mould having been removed to show the details of construction; and

- Figure 9 is a top plan view of a separable mould for casting cladding metal onto the surface of a cylindrically shaped backing slab.

-With aview to practicing my invention, a steel backing slab 20, Figure l, of suitable size is cleaned on the welding surfaces, preferably by sand blasting, and then lowered into a molten bath 21 of viscous substance in a suitable container 22. The container 22 may be. heated by any suitable means, such as by gas supplied by the nozzle 23, to maintain the molten bath 2| in the molten state for preheating the, backing slab 20. An eye may be threaded into the top of the backing slab 20 to permit it to be picked up by a hook 25 of a crane for lifting the backing slab 20 into and out of the container 22. After the backing slab 20 has been preheated to the desired extent, it may be removed from the container 22 and transported to the mould shown generally at 26 in Figures 3 and 4 of the drawings. As shown at 21 in Figure 2, the surfaces of the backing slab 20 are. covered by a layer 21 of the material forming the bath 2|, so that during transit to the mould 26 the surfaces are prevented from coming into contact with the air and are, therefore, not oxidized.

' with a view to centering the backing slab 20.

in the space provided therefor in the mould 26, guide members 28, in the form of steel plates,

may be welded to the upper and lower corners,

The chemistry of the bath 2| is dependent on the combinations of metals to be clad and the required preheating temperatures. The required properties are, a relatively low melting tempera- Figure 41s a top plan view of themould and backing slab shown in Figure 3;

. Fl 5 and 6, respectively, are side and front elevatio a1 views of a valve that maybe emture and a relatively high viscosity at tempera- .tures well above the melting temperature. For

instance, for preheating temperatures around 2300" F. Ihave found that a mixture of about borax and 20% by weight boric acid is suit able. The fusing temperature and viscosity of the bath 2| may be'lncreased by adding more before the-backing The backing slab 20 is left in the bath 2| of (Figures 5 and 6), having a handle 42 at its upper end, is adapted to be slidably mounted in a suitable groove 43 that, as shown in Figure 4, opens into the mould space 33. The valve 4| may be formed of a suitable piece of steel strip and at its lower end it is arranged to completely close the gate 38. On cooling of the cladding metal 33, the portion thereof that remains in slag or flux until it is'thoroughly preheated. The I time required is usually about one hour for each inch of thickness of the slab 20. During preheating the surface of the slab is perfectly sealed from the atmosphere by the bath 2| and, on removing it from the bath 2| for transporting to the mould 26, a layer of the slag or fiuxforming the bath 2|, of about in thickness, clings to its surface as indicated at 21 in Figure 2. As a result of numerous tests on slabs preheated in a bath 2| having the correct composition, I have found, on cooling the slab to room temperature, that its surface under the coating .21 is clean and entirely free from 'oxidation. The

layer 21 of slag or flux hardens on cooling below its melting tempe ature and may readily be broken off. Howev 1', during transit of the slab 20 from the bath 2| to the mould 26, or until the layer 21 is cooled below its melting temperature, it clings to the surface of the slab 20 and will stand relatively rough handling without exposing the slab surfaces to which cladding metal is to be applied. If the slab 20 is scraped against an object during transit to the mould 26, the

layer 21 parts but quickly closes before apprea tongue and a groove 36, respectively, to

prevent the escape of the cladding metal along the parting line of the mould 26. If desired, suitable clamping means may be provided for insuring that the sections 3| and 32 will not be separated while the cladding metal ,is being poured.

The bottom pouring of the cladding metal is accomplished by means of, a pouring sprue or spout 31 having at its lower end a gate 38 that opens into the mould space 33 at the bottom thereof. The cladding metal 39 is poured into the sprue or spout 31, as indicated by. the stream of molten cladding metal 40, and it fills the mould space 33 from the bottom thereof. As the cladding metal 33 rises upwardly in the mould space 33, the slag or fluxlfrom the bath 2|, as indicated by the reference character 21, and other inclusions, will float to the surface readily, as

indicated. It will beobserved that the pouring sprue or spout 31 is positioned along the parting line between the two sections 3| and 32 of the mould'26. This is an important feature of my invention, for it facilitates the separation of the two sections 3| and 32 after the cladding metal has solidified,

In order to further facilitate removal of the mould sections 3| and 32, a valve member ll faces of the sections 3| and 32 are provided with the. pouring sprue or spout 31 will be separated from the rest of the claddingmetal in the mould 26 by the closing of the gate 38 with the valve 4|.

In order to prevent the cladding metal 39 from welding to the surfaces of the mould 26 with which it comes in contact, and the valve member 4|, these'surfaces are provided with a suitable covering material, such as graphite, before the backing slab 20 is'inserted. The cladding metal then welds only to the surfaces of the backing slab 20 in the intended manner, and it is a simple matter to remove the mould 26 therefrom. By having the sprue or spout 31 at the parting line of the mould sections 3| and 32, the metal that solidifies therein is easily removed on parting, so that themould members 3| and 32 may again be used. Thus, if the sprue 31 were entirely within one or the other of the mould sections' 3| or 32, it would be diflicult to remove the solidified metal therefrom after cooling.

The cladding metal 33 is generally of a char acter that cannot readily be cast in a mould of the open-face type. This is particularly true whenthe composite slab is intended to have a smooth, rollable surface after casting and bonding of the facing metal onto the backing slab so that separation will not occur on subsequent working. Metals, such as pure copper, and copper alloys such as high nickel-copper alloys and 'copper-nickel-zinc alloys, are, in the molten I have found that othefcopper alloys such as silicon-nickel-copper alloys, can be readily cast onto backing slabs in accordance with my invention. 1 The nickel in these alloys is employed to facilitate bonding to the backing slab and the silicon-nickel, in combination. forms nickel silicides for the purpose of making the copper more refractory, so that it has substantially the same compression resistance in rolling or working as the steel backing slab. This is of particular importance for copper clad'steel that is clad on two or more sides, since such composite slabs are often rolled into products such as I-beams, Z-bars,

and the like, on suitably shaped rolls. Such products require diamond, oval, and other irregularly shaped passes and, of course, it is essential thatthe two metals forming the composite For example, theresistance to compression or force of the rolls with the same compression rate at 1600'? F. for wrought iron of about 0.02% carbon, mild steel of, about 0.08% carbon, and

1 medium steel of about 0.45% carbon-is, respect1vely,,-l4,000--2l,000 and 33,000 lbs. per sq. inch.

To secure the same properties in the composite slab so that it rolls as if it were made'of a single and 1.5% to 2.0% nickel. I find that, if the nickel content is kept slightly in excess of the silicon content, bonding is greatly facilitated without requiring any extended soaking with the copper in the molten state. This also seems to eliminate any hot or cold short ranges in annealing or rolling.

In Figures '7 and 8 of the drawings I have illustrated a mould, shown generally at 46, that comprises sections 41 and 48 .for receiving in a mould space 48 provided thereby a backing slab 49. In this embodiment of the invention the backing slab 49 is to be provided with cladding metal on two sides ,only and, therefore, the other sides are not intended to be clad and are arranged to fit snugly against the ends of the mould space 48, as illustrated. A suitable eye 50 may be provided for lifting the backing slab 49 from the preheating bath, such as the bath 2| shown in Figure l of the drawings, to the mould 46. The layer of slag or flux from the bath serves to protect the welding surfaces of the backing slab 49 from oxidation, as previously described. The sections 41 and 48 are provided, respectively, with a tongue 53 and a groove 54 to prevent escape of the molten cladding metal along the parting line of the mould. A .pour- 56 at the bottom to provide for bottom pouring of cladding metal into the mould space 48' for the reasons set forth hereinbefore. It will be observed that the gate 56 extends across the bottom of the mould space 48' to permit the flow of the molten cladding metal into the spaces between the surfaces of the backing slab 49 to .be cladded and the opposite walls .of the mould sections 41 and B8. A suitable valve member 51 having a handle 58 is provided in a suitable recess 59 for separating the molten cladding metal designed for applying cladding metal to the surface of a backing slab 63 having a generally cylindrical shape. As shown, the backing slab 63 is provided with an eye 54 for lifting it into and out of the preheating bath, such as the bath 2| shown in Figure 1 of the drawings, and transporting it to the mould 60. During transit the backing slab 63 is protected by a layer 65 of slag or flux that is picked up from the-bath 2| as previously described. The sections 6| and 62 may be provided with an interfitting tongue 61 and groove 68 along the parting line to prevent escape of the cladding metal-in the molten state. A pouring sprue or spot 69 may be provided along the parting line for bottom pouring of the clad- 1 ding metal, and a valve member 10, similar to 1 and described.

ing sprue or spout 55 is provided having a gate in the pouring sprue or spout and the gate 56,

a separable mould comprising 'sections El and 62 that is of the same general construction as describedhereinbefore, but which is especially I claim as my invention:

l.- The method of making and preparing a composite slab for subsequent rolling which com-- prises, preheating a steel backing slab, coating the surfaces to be clad with slag, enclosing the preheated and coated slab in an open top mould, filling the mould space through a pouring spr-ue communicating with the bottom of the mould, projecting a displacing member downwardly into the sprue adjacent the mould space while the metal in the sprue is molten, and allowing the molten copper in the sprue passageway, and mould space to solidify.

2. The method of making and preparing a composite slab for subsequent rolling which comprises, preheating a steel backing slab, coating the surfaces to' be clad with slag, enclosing the preheated and coated slab in an open top vertically divided mould, filling the mould space through a pouring sprue communicating with the bottom of the mould, projecting a displacing member downwardly into the sprue adjacent the mould 

